The bonding reaction between avidin and biotin is well known and forms the basis of various immunoenzymatic techniques for the detection, localization and quantitation of antigens and antibodies. This is described, for example, in J. Histochem. and Cytochem., Vol. 27, No. 8, 1131-1139 (1979), J. Histochem and Cytochem., Vol. 29, No. 4, 577-580 (1981), and Methods in Enzymology, Vol. 62, 308-315 (1979). In these prior art procedures, biotin is attached to a desired molecule by means of biotin-N-hydroxysuccinimide ester. The use of caproylamidobiotin-N-hydroxysuccinimide ester to attach biotin to an antibody is disclosed in Clin. Chem. 25/9, 1572-1580 (1979), and the resulting agglutination titer with respect to avidin was compared to biotinylated molecules prepared using biotin-N-hydroxysuccinimide ester. No difference in agglutination titer was seen. Caproylamidobiotinylated alkaline phosphatase and polymers thereof useful in DNA probes are disclosed in Proc. Natl. Acad. Sci. U.S.A., Vol. 80, 4045-4049 (July 1983).
It is known that biotinylated materials, such as biotinylated peroxidase, used in these prior art techniques can readily lose their ability to bond with avidin upon storage prior to eventual use in an immunochemical procedure.
There is no disclosure in the known prior art of caproylamidobiotinylated horseradish peroxidase or that such modified peroxidase would have improved storage stability and immunohistochemical functionality as compared to conventional prior art biotinylated peroxidase.